The synthesis of new beta-Ga2O3 microstructures was achieved through rapid annealing of GaSe single crystal at 850 degrees C in oxygen-ammonia co-flow for 30-120 min duration. The obtained micro-flowers and micro-leaves were carefully characterized through X-ray diffraction, scanning electron microscopy and Raman spectroscopy. SEM images demonstrated that the product consisted of flower-shaped microstructures, which as time elapsed evolved into leaves-like dendritic microstructures. These microstructures started off directly from oxidized single crystal. A possible growth mechanism was also proposed. Experimental results evidenced that synthesized microstructures exhibited good photocatalytic activity, better than commercial TiO2 powder (Degussa P25). (C) 2015 Elsevier B.V. All rights reserved.